Over past decades, fluoropolymers have found more and more applications, ranging from optical devices, corrosion-resistant coatings, fuel cell membranes, to elastomeric materials. There are a variety of fluorinated monomers suitable for the preparation of fluoropolymers, such as tetrafluoroethylene (TFE), trifluoroethylene (TrFE), chlorotrifluoroethylene (CTFE), vinylidene fluoride (VDF), vinyl fluoride (VF), hexafluoropropene (HFP), pentafluoropropene (PFP), tetrafluoropropene (TFP), trifluoropropene (TrFP), and perfluoroalkylvinyl ether (PAVE), etc. Among these fluorinated monomers, 1,3,3,3-tetrafluoropropene (CF3CH═CFH; HFO-1234ze) is one of the least studied monomers. Due to the low reactivity of 1,3,3,3-tetrafluoropropene monomers with respect to radical polymerization, 1,3,3,3-tetrafluoropropene homopolymer and 1,3,3,3-tetrafluoropropene/tetrafluoroethylene copolymer have only been made by radiation-induced polymerization at high pressures between 5,000 and 15,000 atm. See J. Polymer Sci. A: Polym. Chem. (1973) 11, 1973-1984. This method makes it extremely difficult to produce 1,3,3,3-tetrafluoropropene homopolymer and copolymers on an industrial scale. Copolymers of vinylidene fluoride (CF2═CH2; VDF) with one of several fluorinated monomers, including 1,3,3,3-tetrafluoropropene, was claimed in GB Patent No. 1,281,976. However, this patent provided little information regarding the synthesis of such copolymers.
There remains a need for new fluoropolymers and new methods of making such fluoropolymers. The present invention addresses this need.
Biofouling is any non-desirable accumulation and growth of living matter on wetted surfaces. It is a significant, world-wide problem in almost every industry that relies on water-based processes. Industries particularly affected by biofouling include the pulp and paper manufacturing industry and the food industry, as well as industries connected to underwater construction, ship building, fish farming and water desalination, to name just a few.
One approach to prevent biofouling is the use of non-toxic coatings that create hydrophobic surfaces to which microorganisms cannot attach. Fluoropolymers are generally considered useful with respect to preventing biofouling because of their non-stick and friction reducing properties.
Similar to biofouling, the non-desirable accumulation of ice on surfaces is often a problem in certain industries. One way to address this problem has been to use non-toxic coatings that create surfaces that do not allow ice to accumulate.
Research has shown that the optimal surface energy for resistance to biofouling in marine environments is always between 20 and 30 mJ/m2. See J Mater Sci: Mater Med (2006) 17:1057-1062. So far, few fluoropolymers have been shown to produce this particular surface energy range. For example, on one hand, poly(tetrafluoroethylene) (PTFE), poly(hexafluoropropylene) (PHFP), and poly(2,3,3,3-tetrafluoropropene) (poly-1234yf) have a surface energy below 20 mJ/m2; on the other hand, the surface energy of polyvinylidene fluoride (PVDF) and polychlorotrifluoroethylene (PCTFE) is around 30 mJ/m2. Only one fluoropolymer, polytrifluoroethylene (PTrFE), was reported to have a surface energy within the range of 20 to 30 mJ/m2.
There remains a need for improved methods and articles of manufacture for the prevention of biofouling and accumulation of ice on surfaces. The present invention addresses this need.